Christer Fuglesang
Professor of Space Physics
From space there is a continuous flow of radiation and very small, sub-atomic particles. They originate from close sources such as the Sun, as well as distant galaxies. The most common particles include protons and atomic nuclei, although there can be enormous variation in their kinetic energy. An atomic nucleus that weighs only 10-24 grammes can in some cases have just as much energy as a hard tennis serve.
These ultra-high-energy cosmic particles react with air molecules high up in the atmosphere to create an immense shower of sub-atomic particles. This shower can be several hundred kilometres long, and consist of 100 billion particles. On average, just one particle per square kilometre every hundred years will fall to Earth with the energy of a hard tennis serve.
The international space station, ISS, offers many unique research opportunities with focus on weightlessness, as well as the fantastic perspectives of both space and Earth. KTH is involved in a project with the aim of sending up a detector to ISS in order to film and study the tracks created by ultra-high-energy cosmic radiation in the atmosphere. From a height of 400 kilometres, the detector can see surfaces many times larger than can be seen by any detector on the ground. This research is opening up a new window for astronomy and increasing understanding of ultra-high-energy cosmic particles.